Electrical and materials properties of ZrO2 gate dielectrics grown by atomic layer chemical vapor deposition

Structural and electrical properties of gate stack structures containing Zr O2 dielectrics were investigated. The ZrO2 films were deposited by atomic l ayer chemical vapor deposition (ALCVD) after different substrate preparatio ns. The structure, composition, and interfacial characteristics of these ga te stacks were examined using cross-sectional transmission electron microsc opy acid x-ray photoelectron spectroscopy. The ZrO2 films were polycrystall ine with either a cubic or tetragonal crystal structure. An amorphous inter facial layer with a moderate dielectric constant formed between the ZrO2 la yer and the substrate during ALCVD growth on chemical oxide-terminated sili con. Gate stacks with a measured equivalent oxide thickness (EOT) of 1.3 nm showed leakage values of 10(-5) A/cm(2) at a bias of -1 V from flatband, w hich is significantly less than that seen with SiO2 dielectrics of similar EOT. A hysteresis of 8-10 mV was seen for +/-2 V sweeps while a midgap inte rface stare density (D-it) of similar to 3 x 10(11) states/cm eV was determ ined from comparisons of measured and ideal capacitance curves. (C) 2001 Am erican Institute of Physics.